Cement material and method of producing.



A. S. DWIGHT & R. L. LLOYD. CEMENT MATERIAL AND METHOD OF PRODUCING.

APPLICATION FILED DEC. 30,1912.

Patented Nov. 5, 1918.

2 SHEETSSHEEI I Wane/00% 1/ I A. S. DWIGHT & R. L. LLOYD.

CEMENT MATERIAL AND METHOD OF PRODUCING.

APPLLCATION FILED DEC. 30. 1912.

1 ,Q83,83. Patented Nov. 5, 1918.

.2 SHEETS-SHEEI 2- Wy n i (Juana/ tow W fi" a 7 4 WWW ARTHUR S. DWIGHTAND RICHARD LEWIS LLOYD, OF NEW YORK, N. Y., ASSIGIHORS TO DWIGHT &LLOYD METALLURGICAL COMPANY; OF NEW YORK, N. Y., A CORPORA- TION OF NEWJ'ERSEY.

CEMENT MATERIAL AND METHOD OF PRODUCING.

Specification of Letters Patent.

Application filed December 30, 1912. Serial No. 739,358.

To all whom it may concern:

Be it known that we, ARTHUR S.-"DWIGHT and RICHARD L. LLoYD, citizens ofthe United States, residing at New York,'in the county of New York andState of New York, have invented certain. new and useful Improvements inCement Materials and Methods of Producing, of which the following is aspecification, reference beinghad therein to the accompanying drawing.

Our invention relates to the art of producing hydraulic cement and has'for itsobject to treat the initial mass of material from which thecement is formed more economically and thoroughly and in a mannersuperior to what has been possible by the processes heretofore in vogue,and to there by secure a novel and superlor product.

In one of the methods very commonly employed in the manufacture ofcement the reduced raw cement material is fed into a long rotary kiln inwhich is maintained an intense heat, commonly produced by the combustionof powdered carbonaceous fuel, which is projected, through suitableburners, into one end of the kiln, forming a cone of vflame andincandescence products of combustion, to which the material beingtreated is subjected, and under the influence of which it is convertedinto the clinker, which on being discharged from the kiln and cooled isground to form cement. The apparatus employed in the process justreferredv to is cumbrous, and expensive in its initial construction, aswell as in operation and up keep, while the resulting product isinferior to that of the process constltuting the invention which is tobe hereindescribed, in that it does not have that uniformity ofcomposition and character throughout, nor possess these desirablephysical quallties which characterize the product of our invention.

For, notwithstanding the fact that the rotary cement kilns referred toare made long, and the material being treated, as it is slowly fedthrough the kiln, is agitated and repeatedly turned over and over,nevertheless it tends to accumulate and pile up in the lower portion ofthe kiln where it is often a foot or more in depth, so that it isnot-.at any time uniformly subjected to the action of the flame andburning fuel within, the kiln, it being manifest that the uppermost orexposed particles of the mass are much more charge-a purely physicalresult-and the breaking down of the chemical constitution of theingredients to such an extent as to drlve off or eliminate all water ofconstitution, and all carbonic acid gas which they may contain. From themoment these chemical changes begin to take place other reactiorscommence and new chemical combinations are formed, resulting in theproduction of complex silicates; and finally, before the material isdischarged, these silicates become agglomerated or sintered intomassesforming the cement clinker,the product of the kiln.

The chemical reactions taking place within the kiln, especially theformation of new compounds such as referred to, like most other chemicalcombinations, especially those resulting in the formation of crystals orcrystal-like bodies, take place more readily and perfectly when theparticles throughout which the reactions are taking place are in a stateof quiescence, since agitation-of the particles tends to retard orinterfere with such reactions.

It thus follows that not only does a rotary kiln treatment of cementmaterial tend, by reason of the rumbling, rolling, tumbling andagitating of the material, as has been stated, to interfere with andprevent the complete elimination of those volatile constituents which itis one of the objects of the calcining operation to drive off, but italso interferes with those reactions which result in the formation ofsuch new compounds as Patented Nov. a, rare.

the shell parts, being incompletely dehydrated and freed from carbonicacid gas.

These nodules tend to increase in size, thus reducing the ossibility ofthe interior portions becoming, forming into the complex silicatessought to be produced, while the exterior portions become overburned,excessively hard and refractory and troublesome and expensive to rind.

g The product of the rotary kiln treatment is thus a clinker formed ofmasses which while varying in size are all too small for the mosteconomical handling and treatmentas compared with the product of ourinventionare excessively indurated and refractory in nature, and varyfrom each other in chemical and physical features, so that the cementformed from the indin of such clinker does not have idea 1y uni ormconstituency and characteristics. These results, more or lessunsatisfactory, are secured only by an excessive use of heat-produclngfuel, the consumption of which takes place external to the treatedmaterial so that a large proportion of the heat is not utilized toadvantage but escapes, and is lost.

The object of the resent invention is to so treat cement-formingmaterial as to effect a high but practically uniform heating thereofthroughout the entire mass by means of the consumption of a minimumamount of fuel, which is caused to take place within the mass ofmaterial being treated,in contradistinotion to being consumed externallythereto-, and to thereby effect physical and chemical changes, such asthe driving off of water, both of association and of constitution, andof carbonic acid gas, and the formation of new complex silicates, in amanner and to an extent, as to completeness and uniformity, which hasnot, by any process in vogue in the manufacture of cement, beenheretofore accomplished; producing a substantially uniform coherentstratum of material, which is highly porous and cellular throughout, isfriable and easily ound into cement powder, and which w en so ground issusceptible of perfect crystalization or hydration."

The process can be carried out in any one of numerous mechanisms, and wehave illustrated in the accompanying drawings two, such as are suitablefor this purpose, though we do not wish to be understood as therebyrestricting our invention in its useful applications and adaptations tomechanisms of the specific kinds illustrated.

In the accompanying drawings- Figure l is a side elevation, parts beingbroken away, of an apparatus by means of which the present invention maybe carried into efiect, no attempt having been made in such drawing toindicate the relative proportions of parts, nor to illustrate details ofrst properly calcined and then construction such as, to those familiarwith the art will be readily understood and supplied without specificillustration or description, the drawing being largely diagrammatic incharacter.

Fig. 2 is a vertical section taken on the line II-II of Fig. 1

Fi 3 is a. view in elevation and also largely diagrammatic in character,illustrating another form of apparatus by which the invention may becarried out, and also steps of the process not shown in Fig. 1.

Fig. 4 is a transverse sectional view taken through one of theindependent elements of the holder and carrier for the material in themachine illustrated in Fig. 3.

Fig. 5 is a longitudinal sectional View of the apparatus shown in Fi 3taken through the feed hoppers and contiguous parts.

Fig. 6 is a partial top plan View of two of the grate sections orconveyer elements.

efcrring particularly to Figs 1 and 2 of the drawings, A designates thelower portion ofla hopper or receptacle in which may be placed the rockand other raw material from which the cement is to be produced. Thishopper delivers to a crusher B, which may be of any usual or approvedtype and construction, by which the material is reduced to the desiredsize for further treat ment. C indicates the lower portion of anotherhopper or receptacle in which is placed carbonaceous material such ascoal or coke, and which, as shown, delivers to a crusher D. The finelyreduced materials from the crushers B and D pass to a mixing device Ewhere they are commingled. From the mixer the material is delivered,either mediately or immediatel to a hopper or receptacle F which in turndelivers to the mechanism where the calcining and sintering operationstake place. It will be understood that the several elements oftheapparatus thus far referred to are provided with means for regulatingtheir operations so that the proportions of cement material andpulverized fuel may be regulated to a nicet to suit the workingconditions met with, an so that the material delivered to the apparatuswhere the burning, calcining and sintering 116 takes place can beregulated. It will also be evident that these elements of the apparatusmay be more or less widely separated one from the other without in anyway affecting the essential principles of our in vention.

Referring to the mechanism where the calcining of the material and theformation of cement clinker takes place, H designates an air boxconnected by a trunk I with a suction fan J or other air-moving device.The upper end of this air box is open and across it moves a perforatedsupport K for the material delivered from the hopper This support, asrepresented, consists of a pair of endless chains G engaging withsprocket wheels 9 and supportin between them perforated grate bars L. heperforated support for the material thus formed is caused to move slowlyin the direction indicated by the arrow (1 by any suitable drivingmechanism, characterized by a drive pulley and belt M engagingtherewith. The Working portion of the carrier and support for thematerial moves between side walls N which operate to confine thematerial while under treatment at its edges. For setting fire to thecombustible portion of the charge of ma terial delivery from the hopperF we employ an igniter O that is located adjacent to the exposed surfaceof the material. This igniter may be of any suitable kind, thatillustrated consisting of a pair of gas pipes perforated or providedwith burners so disposed as to project a mass of flame upon the surfaceof the ore sufficient in extent and intensity to thoroughly ignite thematerialacross the entire exposed surface thereof. The igniter islocated as close as convenient to the feed hopper F and over the nearend of the air box H. A hood P which is easily removable to permitaccess to parts of the apparatus, is preferably employed, it"being of asize to cover the exposed surface of the body of material which at anyone time is under treatment, its open end being practically coextensivewith the open end of the air 'box H. It is open at go so that theatmospheric air freely enters the hood, and passes through the bed orstratum of material being treated and the perforated support on which itrests and into the air box H, whence it, now charged with products ofcombustion from the burning carbonaceous material, and water vapor andcarbonic acid gas driven oil from the material being calcined, passes tothe fan, and thence to the stack or other offtake conduit.

The perforated grate is slowly moved across the open end of the air boxH, and as it travels below the hopper F receives a' layer of materialtherefrom. The depth of this layer is regulated and its upper surfacemade smooth by the front edge plate f of the hopper, which may be madeadjustable if desired. Five inches may be assumed as the depth of thestratum of material under ordinary working conditions. Soon afterleaving the hopper F the stratum of material is ignited at its uppersurface, and the combustion thus started becomes internal to the mass,being induced to gradually advance from the ignited to the oppositesurface by the air currents caused by the fan J, these being indicatedin the drawings by arrows. The air currents preferably pass in adownward direction through the mate rial, so that they operate to holdthe particles thereof quiescent; that is, they prevent any agitationamong the particles of the mass, such as would occur should the air movein the opposite direction, or upward, when it would cause more or lessof a lifting action and disturbance. This quiescent state of theparticles of the material being treated is maintained, although the massas a whole is being bodily moved, and continues so long as the internalcombustion within the mass, caused by the burning of the carbonaceousfuel, goes on, the particles being restrained on the side where'the airleaves the mass by the grates K and at the upper exposed surface by thepressure of the down-moving am The movements of the parts of theapparatus are preferably so timed that the combustion in any particularportion or body of the material is maintained so long as that portion orbody is over the air box H; and during such time the zone of combustionpasses from the upper and first ignited surface entirely through themass of material to the lower surface resting upon the grate K. Theamount of fuel, relative to the amount of the cement-forming material,the force of the air currents produced by the fan J, and the speed ofthe mechanism, are so proportioned and regulated that the combustion ofthe fuel constituent of the mass is of such intensity as will cause acomplete and uniform calcining and clinkering or sintering of the massof cement-forming material from surface to surface, at about the timethe product arrives at the point where it is to be discharged from themachine. The treatment described causes the entire layer of materialbeing treated to form into a substantially continuous coherent sinter orclinker cake, which, however, is easily broken off at the delivery endof the apparatus, a breaking roll Q being employed if found desirable.

It has already been set forth that one of the objects of the presentinvention is to produce a cement clinker or sinter that is uniform innature, and whose characteristics after Working conditions have oncebeen ad justed can absolutely be determined and maintained. It might beexpected in carrying out the process thus far described that thematerial, at the opposite surfaces would be insufficiently burned, andthat for that reason the resulting product would not be uniform inconsistency and composition from surface to surface. The reason for thissupposition is apparent, namely, that at the exposed surface whereignition takes place, the material is not subjected to so great a degreeand so long continued application of the heat, as are the other portionsof the mass, while at the same time its temperature will be reduced bycontact with the air. At the opposite or lower surface the materialrests directly upon a metal grate or support, which is a good conductorof heat, with the result that here also the efl'ect upon the material ofthe internal combustion taking place vwithin the mass is somewhatdiminished.

Therefore, in order to guard against such insufficient treatment of thematerial at its upper and lower surfaces we have devised the mechanismas illustrated in Fig. 4. This in most of its features is similar inprinciple to the apparatus illustrated in Figs. 1 an 2 It has a hopper Afor the raw material to be treated arranged to deliver to acrusher B.This in turn delivers upon a conveyer R to which also is deliveredcrushed carbonaceous fuel, which is represented as being supplied from ahopper D. The conveyer R deliversto a mixer E and this in turn to thefeed hopper F.

Adjacent to the feed hopper and arranged to deliver to the support forthe material is another hopper S adapted to contain a charge of burnedcement clinker, with which is preferably mixed a pulverized carbonaceousfuel, such hopper being arranged to deliver a thin layer directly uponthe perforated bottom of the carrier or support for the material, whichlayer acts as a protecting cover between the metallic grate bars and thelayer of material to be treated and delivered from the hopper F,preventing the unburned material from coming into direct contact withthe material of the grate or support.

T represents another hopper or receptacle in which is placed pulverizedcarbonaceous fuel, or a mixture thereof and already burned cementmaterial. From this hopper a thin protective layer is fed upon the layerof material to be treated. By this arrangement we are enabled to securea product practically having the uniform characteristics so muchdesired.

The supporting and conveying mechanism illustrated in Fig. 4 differsfrom that shown in Fig. 1 in that the support for the material is madeup of a series of independent pallets U. These are each provided with aperforated bottom and are referably open ended, though provided wit sidewalls, so that when in train they constitute an elongated continuoustrough with a perforated bottom and closed sides, but open at the top.These pallets are directed in their course by the tracks and guidepieces V, V so that they are caused to follow an endless path, motionbeing imparted to them by wheels W.

By disposing the material to be treated in athin layer such as describedit is entirely practicable to carry out the process without thenecessity of using strong air currents, and without subjecting the lowerportions of the bed or stratum of material to the weight of a deep bodyof superposed material which would have a tendency to so pack andconsolidate the material as to cause the perforated grate or aircurrents to permeate the mass irregularly forming blow holes andchannels, instead of following the interstices or passages naturallyformed by depositing a loose pulverulent mass in a thin layer orstratum.

The combustion of the pulverized carbonaceous fuel causes the dehdration of the raw cement material, a comp ete calcinin thereof, and asintering or agglomeratlng together of its particles, producin thecontinuous sinter cake or mass alrea y referred to. During suchcombustion large uantities of gaseous products are produce which, withthe air that is caused to pass through the material, maintains or keepsthe sinter mass being formed in auniformly highly porous condition,which characterizes the finished product of our process. The burning outof the carbonaceous portion of the charge leaves voids in the mass andcauses it to more or less contract or shrink so that the resultingclinker or sinter is friable and easily reduced to powder by thegrinding operations which follow the calcinlng and sintering in order toproduce the cement of commerce- This grinding is much more easilyeffected than is the grinding of the cement clinker made by otherprocesses of which we are aware, since the prgduct of the sinteringmachine is uniformly cellular and porous, the walls of materialseparating the ores or voids of the mass being thin and ence easilybroken down by the grinding machinery.

What we claim is 1. The herein described process of producing hydrauliccement, which consists in finely reducing the raw cement materials,finely reducing a solid carbon fuel, intimately and umformly comminglingthe reduced carbon fuel with the cement material, forming a. thinstratum of the commingled masses, igniting the fuel component at onesurface of the stratum, forcing air throu h the stratum from the ignitedsurface whilet e fine particles are held in quiescence, causiu arelatively thin zone of combustion to gra ually traverse the strartumfrom the ignited surface to that opposite thereto, causing the heatgenerated by the combustion to release the carbon dioxid from thecarbonates and at the time of nascency of the earth bases causing thesilica to unite with said bases and form the silicates characteristic ofcement, and maintaining the conditions of memes rial, covering the saidlayer of mixed material with a layer containing fuel without theadmixture therewith of raw cement material,

setting fire to the last said added layer, and passing air through theentire body of material to cause the combustion of the carbonaceouscomponent thereof from surface 'to surface.

3. The herein described process of producing hydraulic cement whichconsists in thoroughly and intimately commingling finely reduced fuelmaterial with finely reduced raw cement material, depositing thismixture in a thin layer pervious to air, covering said layer of mixedmaterial with a ,thin layer of slowly-burning fuel, setting fire to thesaid covering fuel layer, andpassing air through the entire body ofmaterial to cause combustion of the fuel content of the mixture and thesintering of the cement-forming material. 7

In testimony whereof we aflix our signatures, in presence of twowitnesses.

ARTHUR S. DWIGHT. RICHARD LEWIS LLOYD. Witnesses:

J OHN 'KNox, WILLIAM J. HoLLEN.

